Characterization of a dominant antigenic determinant ofPar oI encoded by recombinant DNA

摘要

SummaryBackgroundThe pollens fromParietaria judaicaandParietaria officinalisare a major cause of pollinosis in Europe.Par oI (13.5 kDa) andPar jI (12 kDa), the major allergens from these species, are highly crossrcaclive.MethodsWe have immunoscreened aP. judaicapollen cDNA expression library with a rabbit antiserum specific forPar jI and with a serum pool from allergic patients. An immunopositive clone containing a 26 bp insert was further characterized. The insert sequence was determined and the beta‐galactosidase fusion protein was partially purified by electroelution from sodium dodecyl sulfatc‐poblyacrylamide gel electrophoresis (SDS‐PAGE) gels.ResultsThis fusion protein specifically and extensively inhibitedPar oI andPar jI binding of a rabbit antiserum and of a serum pool obtained from allergic patients. The antifusion‐protein antiserum obtained in a rabbit (anti 6a) specifically precipitated radioiodinated purifiedPar oI in the double antibody radioimmunoassay (DARIA) and competed with antibodies of sera from allergic patients for the binding toParietariapollen extract allergens by enzyme linked immunosorbent assay (ELISA). We investigated the prevalence of antibody response towards the 6a epitope in patients naturally sensitized toParietaria. The presence of 6a specific IgE antibodies was assessed in the sera of 33 patients using inhibition assays. All sera had antibodies with this specificity: the extensive percentage of inhibition reached suggested that they dominated individual ab response.ConclusionIn conclusion, the antibody response induced by natural exposure to the pollen ofParietariaappears to be higly focused on a single linear antigenic determinant of the major allergens which may play a relevant role in the development of clinical allergy. This report is, to our knowledge, the first description of a dominant linear epitope of a major a